258 Allgemeines. — Morphologie etc. 



les progres croissants du microscope, on etablit la generalite de 

 la sexualite et de la fecondation dans le regne vegetal, 



A partir de cette epoque, la Botanique et la Zoologie evoluent 

 en raeme temps. II natt une science des etres vivants, la Biologie. 

 Darwin imagine une hypothese generale de l'heredite, la Pange- 

 nese que de Vries reprend en la perfectionnant sous le titre: 

 Pangenese intracellulaire (1878). Fondee sur les recentes de- 

 couvertes de Strasburger (1876) sur la formation et la division 

 des cellules, eile Oriente Weissmann qui distingue un plasma 

 somatique et un plasma germinatif, qui fait decouvrir la reduc- 

 tion chromatique, sa generalite et son importance pour la defi- 

 nition de la sexualite. Le chromosome devient l'unite fundamentale 

 dont la continuite se suit ä travers les individus. Les decouvertes 

 de Mendel, reprises en 1900, donnent une grande cohesion et une 

 force demonstrative ä tout ce Systeme. II faut noter qu'on est parti 

 de l'identite cellulaire de l'organisation pour aboutir ä la differen- 

 ciation specifique, ä la discontinuite chimique des especes. 



L'influence de Darwin s'est fait encore sentir en provoquant 

 la recherche de la parente reelle des groupes naturels. La conception 

 du transformisme a fourni des points de depart pour un nouvel 

 essort de la geographie des etres vivants, des relations des plantes 

 avec les insectes, de la biologie florale. „Au lieu de peser les carac- 

 teres et de determiner leur importance d'apres leur frequence rela- 

 tive, methode propre aux sciences chimiques, on etablit des series 

 de variations dans le m6me sens, on cherche la continuite et la 

 filiation." 



L'histoire de la Botanique reflete les idees de l'epoque et les 

 methodes en honneur sont alternativement Celles des physiciens ou 

 celles des chimistes. L. Blaringhem. 



Kuwada, Y., Maiosis in the Pollen Mother Cells of Zea 

 Mays L. (Bot. Mag. Tokyo. XXV. 294. p. 163-181. 1 PI.) 



The author gives the following summary at the end of his paper. 

 The gemini in Zea Mays var}^ in number from 9 — 12. Even in one 

 and the same race (the autor made his researches on several races 

 of the species) there are certain variations. 



The sugar corns have generally a larger number and the starch 

 corns smaller; and there seem to exist certain connections between 

 those two kinds of numbers of gemini, and it is likely that the 

 smaller numbers were reduced from 12 and consequently the num- 

 ber 12 is original for all the races of Zea Mays. 



The size and shape of gemini are tolerably different as shown 

 in the side view of the metaphase, and there are two sets of them, 

 that is, each sort of gemini is duplicated. In the equatorial plate of 

 the homotype division some pairs of chromosomes come in contact 

 with each other or even fuse up altogether. 



Those two facts, chiefly the former, lead to the view that Zea 

 Mays is probably a tetraploidal plant, not necessarily apogamic. 



It is suggested that the production of innumerable races of Zea 

 Mays has a certain relation with the duplication of chromosomes, 

 resulting in the double number derived from an original form, which 

 had probably 6 chromosomes in reduced number. 



An abnormal case was found in a race „Amber rice pop com." 

 The geminial chromosomes, though not all, separate from each 

 ottier without Intervention of the traction fibres, and the individual 



